Process of alkylating aromatic hydrocarbons



May 7, 1946.

R. E. BURK ET AL PROCESS OF ALKYLATNG AROMATIC HYDROCARBONS Filed Dec. 16, 1944 Patented May 7, `1946 PROCESS OF ALKYLATING AROMATIC HYDROCARBONS Robert E. Burk, Wilmington, Del., and Everett C, Hughes, Cleveland Heights, Ohio, assignors to The Standard Oil Company, Cleveland, Ohio, a

corporation of Ohio Application December 1s, 1944, serialI No. 568,558 14 claims. (c1. 26o-671) This invention relates to the alkylation of aromatichydrocarbons in the presence of hydrogen fluoride as a catalyst in the vapor phase promoted by boron fluoride.

It has been known to alkylate aromatic hydrocarbons with propylene or higher oleflns by hydrogen fluoride as catalyst, without a promoter. While operative with these oleflns, the hydrogen fluoride is not sufdclently active for ethylene, giving for instance but little more ,than sixty per cent conversion of ethylene, whereas propylene is reacted completely. We have now found however, that alkylation may be so directed, by suitable process steps and conditions, as to react ethylene particularly successfully, and also to form selectively mono-alkylated products of higher alkylated products as may respectively be desired.

To the accomplishment of the foregoing and related ends,- the invention, then, comprises the features hereinafter fully described, and particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative however of but a few of the various ways in which the principle of the invention may be employed.

Oleflns which may be `used are notably thosel which are normally gaseous, as ethylene, propylene, butylenes, mixtures of olens, or olefin-paraihn mixtures. Refinery gases containing both paraiiins and oleiins may be conveniently used without separation, and an especial. advantage of l the invention is the ability to operate with dilute olefin-containing gases. The oleflns may be reacted with aromatic hydrocarbons such as benzene, toluene, etc. If it is desired to produce particularly mono-alkylated aromatic compounds the ratio of olefin and aromatic hydrocarbon should be in the order of up to 15, and usually 3 to 15, mois of aromatic to each mol of olefin. If the production of higher alkylates is desired, this ratio should be reversed.

A further factor favoring mono-alkyl derivatives is the application of hydrogen uorlde as catalyst in the vapor phase. This catalyst is promoted, in particular by providing a smaller amount of boron fluoride as promoter. The amount of hydrogen fluoride catalyst applied may be from 1 to 40 weight per cent (based on the aromatic), depending upon the extent of action desired, and usually preferably around 5-15 weight per cent. The promoter, boron fluoride, may be supplied in such minor proportionsas from y; to 20 per weight per cent (based on the aromatic) The operating conditions should include a temperature at which the reaction proceeds at a satisfactory rate, and a pressure to assure that the hydrogen fluoride and boron fluoride are in the vapor phase at'. said temperature. The olefin generally is in the vapor phase and the aromatic will be in the liquid or vapor phase, depending on the temperature and pressure conditions. The temperature may be selected, among other things, in relation to the amount of the catalyst employed, the relative proportions of the iluorides, and the speed of the reaction desired. The lower temperature limit is that. at which the reactionproceeds at a. desired rate and the upper temperature limit is one in which the alkylation of aromatics is still the primary reaction. A temperature for suitable operating conditions can readily be selected in view of this explanation. In a commercial operation which takes into account economic and other operating factors, a temperature within the range of 0 to 375 F. probably will be selected. and within this range a tempera- -ture of to 200 F. is preferred. 'I'he pressure may be any pressure except that it must not be so high as to cause either of the fluorides to be in the liquid phase at the prevailing temperature. For example, if the reaction temperature is about 67 F. (boiling point of hydrogen fluoride) the pressure in the reaction should not be in excess of atmospheric. `At reaction temperatures below the boiling point of hydrogen fiuoride, the pressure would be less than atmospheric. However, in order to obtain desirable reaction rates and high yields in a reasonable time, temperatures somewhat above 67 F. are generally employed and it is therefore possible to use super-atmospheric pressure, vsuch as in excess of 50 pounds per square inch, and at much higher temperatures up to 500 pounds per square inch.

The catalyst componentsv all or in part may be brought in with the aromatic hydrocarbon, where preferred. In one desirable mode of operation, the promoter, boron fluoride, is mixed with the olefin and this mixture is then partially saturated with hydrogen fluoride to provide the latter in the desired catalytic amount, and the resulting gas mixture is then passed through an agitated pool of the aromatic hydrocarbon which is to be alkylated.

It is advantageous to recover or absorb the catalyst from the spent gases coming from the reaction zone, and this may be accomplished by contacting them with aromatic feed or with supplementary absorbent or both. And desirably this may be in a counter-current down ilow of the feed or absorbent liquid against the rising gas in tower arrangement, the complete recovery of the catalyst from the off-gas being accomplished and the catalyst being kept in suspension Within the reaction tower. Higher alkylated products which are not desired may be recirculated.

As an example: Benzene and an ethylene-containing gas (ethylene content 4.3%) in a mol ratio of 1 to 0.166 of benzene and ethylene respectively, were reacted in the presence of a catalyst comprising vaporous hydrogen fluoride in amount of 10.5 weight per cent (based on the benzene), promoted by 4.1 weight per cent of boron fluoride (based -on the benzene), the temperature being 110 F. and the pressure 200 pounds per square inch. All of the ethylene was taken up in the reaction, and of the alkylate product 88.64 per cent was monoethyl benzene, penta and hexa ethyl benzenes were present in only a trace, and the remainder was per cent diethyl benzene and 1.16 per cent of tri and tetra ethyl benzenes.

As a further example: Benzene and a gas containing 5% ethylene were reacted in a mol ratio of 1 to 0.2 of benzene to ethylene respectively in the presence of a catalyst comprising vaporous hydrogen fluoride in an amount of 11.1 weight per cent (based on the benzene) promoted by 5.8 weight per cent of boron triiluoride (based on the benzene) at a temperature of 220 F. and the total pressure of 150 pounds per square inch.

Analysis showed that 83% of the ethylene in the gas was taken up in the reaction; the alkylate product contained 86% monoethyl benzene.

As an additional example: A commercial grade of benzene known as 2 benzene," and a gas containing 11.8% propylene and the balance saturates, were reacted at a temperature of 113 F. at a total pressure cf 102 pounds per square inch. 'I'he reaction was carried on in the presence of a catalyst comprising vaporous hydrogen fluoride in an amount of 21.5 weight per cent (based on the benzene) promoted by a trace of boron trifluoride, i. e., an amount being of the order of 1A to 1 weight per cent or less (based on the benzene). All of theV propylene was taken up from the gas during the reaction, and thealkylate formed comprised 75% isopropyl benzene,

Other modes of applyingthe principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims, or the equivalent of such, be employed.

We therefore particularly point out and distinctly claim as our invention:

1. In a process of alkylating aromatic compounds, reacting ethylene with benzene in proportions of -1 mol of the former to 3-15 mols of the latter by a large amount of vapor phase hydrogen fluoride promoted by a smaller amount of boron fluoride, at a temperature not over 200 F. and pressure at least 50 pounds per square inch, and feeding in cool benzene to the reaction counter-currently to the off-gas of the reaction to recover at least a part of the fluorides therefrom.

2. In a process of alkylating aromatic compounds, reacting ethylene with benzene in proportions of 1 mol of the former to 3-15 mols of the latter by a large amount of vapor phase hydrogen fluoride promoted by a smaller amount of boron fluoride, at a temperature not over 200 F. and pressure at least 50 pounds per square inch. and feeding a cool absorbent counter-currently to the off-gas of the reaction to recover at least a part of the fluorides therefrom.

3. In a process of alkylating aromatic compounds, reacting ethylene with benzene in proportions of 1 mol of the former to 3-15 mols of the latter by a large amount of vapor phase hydrogen fluoride promoted by a smaller amount of boron fluoride, at a temperature not over 200 F. and pressure at least 50 pounds per square inch, and feeding a cool liqlud-counter-currently to the oil-gas of the reaction to recover at least a part of the fluorldes therefrom.

4. In a process of alkylating aromatic compounds, reacting ethylene with benzene in proportions of 1 mol of the former to 3-15 mols of the latter by vapor phase hydrogen fluoride promoted by a smaller amount of boron fluoride, at a temperature not over 200 F. and pressure at least 50 pounds per square-inch.

5. In a process of alkylating aromatic compounds, reacting an olefin which is normally gaseous with a larger proportion of an aromatic hydrocarbon by vapor phase hydrogen fluoride catalyst promoted by a smaller amount of boron fluoride, at a temperature not over 200 F. and pressure at least 50 pounds per square inch, and admixing cool benzene with the off-gas of the reaction to recover at least a part of the fiuorldes therefrom.

6. In a process of alkylating aromatic compounds, reacting an olefin which is normally gaseous with a larger proportion of an aromatic hydrocarbon by vapor phase hydrogen fluoride catalyst promoted by a smaller amount of boron fluoride, at a temperature not over 200 F. and pressure at least 50 pounds per square inch, and admixing a cool absorbent with the off-gas of the reaction to recover at least a part of the fluorides therefrom.

7. In a process of alkylating aromatic compounds, reacting an olefin which is normally gaseous with a larger proportion of an aromatic hydrocarbon by vapor phase hydrogen fluoride catalyst promoted by a smaller amount of boron fluoride, at a temperature not over 200 F. and pressure at least 50 pounds per square inch, and admixing a cool liquid with the off-gas of the reaction to recover at least a part of the fluorides therefrom.

8. In a process of alkylating aromatic compounds, reacting an olefln-containing gas with a larger proportion of an aromatic hydrocarbon by vapor phase hydrogen fluoride catalyst promoted by boron fluoride, at a temperature not over 200 F. and pressure at least 50 pounds per square inch.

9.'In a process of alkylating aromatic compounds, reacting an olefin-containing gas with a smaller proportion of an aromatic hydrocarbon byl vapor phase hydrogen fluoride catalyst promoted by boron fluoride, and admixing cool aromatic hydrocarbon'with the oil-gas of the reaction to recover at least a part of the fluorides therefrom.

10. In a process of alkylating aromatic compounds, reacting an olefin-containing gas with a smaller proportion of an aromatic hydrocarbon by vapor phase hydrogen fluoride catalyst promoted by boron fluoride, and finally admixing a cool absorbent with the oil-gas of the reaction to recover at least a part of the fluorides therefrom.

11. In a process of 'alkylating aromatic compounds, reacting an olefin-containing gas with a smaller proportion of an aromatic hydrocarbon by vapor phase hydrogen nuorlde catalyst promoted by boron fluoride, and finally admixing cool liquid with the ot-gas oi' the reaction to recover at least a part of the'uorides.

therefrom. Y

12. In a process of alkylating aromatic compounds, reacting an olefin-containing gas with an aromatic hydrocarbon 'by vapor phase hydrogen fluoride catalyst' promoted by boron fluoride at a temperature ofvnot over 200 F. and at a pressure of at least 50 pounds per square inch.

13. In a process of alkylating aromatic compounds, reactimg an olen-containing gas with an aromatic hydrocarbon by vapor phase hydrogen uoride cataiyst promoted by boron fiuo- 15 y aan@ ride at a temperature of not over 200 F. and at a `pressure to maintain the hydrogen fluoride and the boron triiiuoride in the gaseous phase at said temperature.

14. In a process of alkylating aromatic com-l y pounds, reacting an olefin-containing gas with an aromatic hydrocarbon by vapor phase hydrogen uoride catalyst promoted by boron uoride at a temperature at which the reaction proi ceeds and at a pressure to maintain the hydrogen fluoride and boron triuoride in the vapor phase at said temperature.

ROBERT E. BURK. Evmmr C. HUGHES.

Disclaimer 2,399,662.-Robert E. Burk, Wilmington, Del., and Everett 0. Hughes, Cleveland Heights, Ohio. PROCESS 0F ALKYLATING ARoMATIc HYDRocARBoNs. Patent dated May 7, 1946. Disclaimer filed May 27, 1949, by the assignee, The Standard Oil Company,

Hereby enters this disclaimer of claim 4, and so much of claims 8, 12, 13, and 14 as is in excess of a process of alkylating aromatic compounds by the reaction of an olefin having not less than three carbon atoms with an aromatic hydrocarbon under the conditions set forth in said claims.

[Ojicfial Gazette June 21, 1949.] 

